The Ultimate Guide to Email Security: Types, Protocols, and Best Practices

Emails offer a mode of communication across businesses, customers, and stakeholders, maintaining a smooth exchange of information between all involved. Email has become an indispensable tool for marketing and communication, playing a pivotal role in facilitating business transactions, fostering customer relationships, offering a convenient medium for information exchange, and much more. However, it can be easily manipulated for malicious purposes if email security is not prioritized, as it is also a common target for cyberattacks. Threats like phishing attacks, malware, and data breaches can pose significant risks to your customers’ data and your company’s reputation. With an estimated 3.4 billion spam emails generated daily and Google banning over 100 million fraudulent emails each day, the threat landscape is vast and growing.

Email security refers to the measures and practices implemented to protect email communication from unauthorized access, data breaches, and malicious activities. It includes various techniques and technologies aimed at ensuring the confidentiality, integrity, and authenticity of email messages.

Email security involves multiple layers of protection to mitigate risks and safeguard sensitive information transmitted via email. Cybercriminals utilize different tactics and activities to jeopardize the security, integrity, and privacy of email communications, which are known as email security threats or email-based threats.

What is Email Security? 

Email security is the process of protecting email communication in the transmission and storage of private, personal, and commercial information sent through email. It includes content filtering, antivirus software, encryption algorithms, and email authentication to ensure data privacy, while at the same time preventing loss or unauthorized access.

Email security best practices are a set of recommended strategies that can help protect electronic communications, such that their intended content is not compromised or altered.

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What are the 3 Types of Email Security?

There are three main categories within which to think about after you know what is email security: digital (scalable), physical (modifiable), and procedural.

1. Digital – It involves making sure your emails are encrypted in transit and at rest, and that they can’t be read by unauthorized parties. This includes technologies like TLS, S/MIME, and end-to-end encryption.
2. Physical – This type of security relates to securing the physical servers and infrastructure where email data is stored. The goal here is to prevent unauthorized physical access, tampering, or theft of the hardware containing sensitive email data.
3. Procedural – It’s about establishing secure processes and policies, ensuring that people who have permission can view or change information in the email system without having malicious intent towards the company itself or its customers. This includes user training, password policies, access control, and incident response plans.

How does Email Security work?

Email security works by implementing a multi-step process often involving:

1. Authentication – This is the process by which you verify that the person or server who sent you an email actually sent it and is authorized to do so. Protocols like SPF, DKIM, and DMARC are used to authenticate the sender’s domain and prevent spoofing.
2. Encryption – This is when you encrypt your data so that only those with authorized access (usually via a private key) can read it. This ensures confidentiality during transmission (using TLS) and potentially at rest (using technologies like S/MIME or PGP). This means nobody else can read it unless they have the necessary decryption key.
3. Protection – Protection refers to the process of defending against various threats, including spam filtering, malware scanning, and blocking phishing attacks by identifying suspicious links, attachments, or content in emails that could compromise your account or lead to the theft of sensitive information (like passwords or credit card numbers).

Why is Email Security important?

Email security is critically important for several reasons, especially given the rising volume and sophistication of email-based threats. Common vulnerabilities and threats include Phishing (including Spear Phishing and Whaling), Business Email Compromise (BEC), Malware distribution (including Ransomware and Trojans), Spoofing, Man-in-the-Middle (MITM) attacks, DKIM Replay Attacks, Zero-Day Exploits, Credential Harvesting, Pharming, and Data Breaches. The number of unique phishing sites discovered globally surged by over 300% between Q2 and Q3 of 2020 alone, highlighting the scale of the problem. Protecting against these threats is essential for:

Safeguarding Confidentiality

Email often contains sensitive information, such as personal or financial data, or business secrets, and it is essential to protect this information from unauthorized access. Without adequate email security measures in place, such information could be easily intercepted and compromised, leading to a loss of trust. A data breach demonstrates a failure to protect sensitive information, potentially exposing customers to identity theft or fraud and subjecting the company to legal action under data protection laws like GDPR.

Preserving the Integrity of Email Messages 

Email messages can be tampered with during transmission (e.g., through Man-in-the-Middle attacks), making it possible for someone to modify the content of the message without the sender or recipient knowing about it. Ensuring the integrity of email ensures that messages remain unaltered during transmission.

Ensuring Availability

Email security is also important to ensure that email systems remain available and usable. Email systems can be targeted by attackers (e.g., through denial-of-service attacks or ransomware), and without proper security measures in place, they can be disrupted, resulting in downtime, lost productivity, and potential data loss.

Protecting Reputation

When a company’s data is compromised, or its domain is used for malicious emails, its reputation takes a significant hit. Trust is difficult to regain once lost, and a tarnished reputation can deter potential customers, lower engagement rates, and negatively impact brand perception.

Preventing Financial Loss

Data breaches and successful email attacks like BEC or ransomware can result in substantial financial losses for businesses. These costs include remediation efforts, legal fees, regulatory fines (e.g., GDPR violations have resulted in nearly €3 billion in fines), compensation to affected customers, and lost business. According to IBM, the average cost of a data breach in 2023 was $4.45 million, and specific attacks like whaling can cost upwards of $47 million.

Maintaining Compliance Standards

Many industries and organizations are subject to various regulations and compliance standards (like GDPR, HIPAA, PCI DSS) that require them to protect sensitive information communicated via email. Implementing robust email security measures, including email archiving and organization where necessary, helps meet these compliance requirements and avoid costly fines and penalties.

Email Security Protocols

There are several standard email security protocols designed to enhance the security of email communication. Here are some of the commonly used protocols:

1. Secure/Multipurpose Internet Mail Extensions (S/MIME)

S/MIME provides end-to-end encryption and digital signatures for email messages. It ensures the confidentiality and integrity of email content by encrypting the message and verifying the sender’s identity.

2. Transport Layer Security (TLS)

TLS is a widely adopted protocol that encrypts the communication between email servers (and between clients and servers), ensuring secure transmission of email data. It protects against eavesdropping and tampering during transit. It uses certificates to establish a secure connection.

3. Sender Policy Framework (SPF)

SPF helps prevent email spoofing by allowing domain owners to specify which email servers (via IP addresses) are authorized to send messages on behalf of their domain. Recipient servers can then verify the SPF record to check the authenticity of incoming emails based on the sending server’s IP.

4. DomainKeys Identified Mail (DKIM)

DKIM adds a digital signature to outgoing emails, linked to the domain name. This provides a way for recipient servers to verify that the message hasn’t been tampered with and is genuinely from the claimed domain by checking the signature against a public key published in the domain’s DNS.

5. Domain-based Message Authentication, Reporting, and Conformance (DMARC)

DMARC combines SPF and DKIM alignment checks to authenticate emails and specifies how recipient servers should handle messages that fail authentication (e.g., quarantine or reject). It helps prevent domain impersonation (spoofing) and allows domain owners to gain visibility into email usage and potential abuse through reports.

6. Internet Message Access Protocol Secure (IMAPS) and Post Office Protocol Secure (POP3S)

IMAPS and POP3S are secure versions of the IMAP and POP3 protocols, respectively. They add encryption (typically using TLS) to the retrieval of email from mail servers, ensuring the confidentiality of email content during client-server communication.

7. Brand Indicators for Message Identification (BIMI)

BIMI enables companies to display their verified brand logo next to authenticated emails in the recipient’s inbox. It relies on DMARC enforcement and helps build brand trust and recognition while further discouraging spoofing.

These protocols work together to provide various layers of email security, including encryption, authentication, and verification, helping organizations protect against unauthorized access, data breaches, and email-based attacks.

Email Security Best Practices

Email security is a crucial part of your online business. If you don’t have robust email security measures, you could be putting yourself at risk for cyber-attacks, data theft, financial loss, and reputational damage.

Fortunately, there are several email security practices that organizations and individuals should implement. Each one contributes to protecting your mailing information and keeping it secure from prying eyes and malicious actors.

Key practices include implementing strong encryption, which protects your messages from being read by anyone who might intercept them; and robust authentication, which verifies that the sender is legitimate. User education and vigilance are also paramount.

Educate Users and Employees

Regular training is essential to help users recognize phishing attempts, understand the dangers of clicking suspicious links or opening unknown attachments, and follow secure practices. Employees should be wary of emails requesting sensitive information or urging immediate action, even if they appear to come from known contacts.

Implement Strong Password Policies

Enforce the use of strong, unique passwords for email accounts and related systems. Passwords should contain a mix of uppercase letters, lowercase letters, digits, and non-alphanumeric characters. Avoid repeated characters and implement policies for periodic password changes (e.g., every 3 months). Discourage password sharing, sending passwords via email/text, or saving them in browsers. Encourage the use of password managers.

Implement Spam Filters

Spam is a type of unsolicited email that often includes harmful or deceptive content, used by spammers, scammers, and hackers. Spam filters identify and block unwanted emails by examining content, sender reputation, and other patterns (using blacklists, keywords, anomaly detection, heuristics). While not foolproof, they significantly reduce the volume of malicious emails reaching inboxes.

Configuring Anti-Virus Protection

Viruses and other malware are major threats often delivered via email attachments or links. Implementing reputable antivirus software on endpoints and within the email server infrastructure is crucial. These systems scan incoming (and sometimes outgoing) emails and attachments for known malware signatures and suspicious behavior, blocking threats before they can execute. Regularly update and patch software and applications to protect against known vulnerabilities.

Using Email Attachment Control and Sandboxing

Malicious attachments are a primary vector for malware delivery. Email attachment control systems can restrict certain file types or scan attachments before delivery. Email sandboxing provides an additional layer by opening suspicious attachments in an isolated environment to observe their behavior without risking the main network. Be cautious of suspicious email attachments or links, even from known contacts, and verify authenticity before clicking or opening.

Enforcing Email Encryption

Unencrypted emails are vulnerable to interception and reading. Encrypting emails ensures that only the intended recipient can decipher the content. Use Transport Layer Security (TLS) to encrypt email transmission between servers. For end-to-end encryption (E2EE), use protocols like S/MIME or PGP, ensuring the message remains encrypted from sender to recipient, even protecting it while at rest on servers. Always encrypt sensitive information before sending via email.

Enable Account Monitoring and Recovery Options

Enable email account activity monitoring to receive alerts for unusual login attempts (e.g., from unknown locations). Set up robust account recovery options (like verification codes or security questions) and enable two-factor authentication (2FA) wherever possible to add an extra layer of security beyond just the password.

Regularly Back Up Data

Regularly back up important email data to a secure, separate location. This allows for recovery in case of data loss due to hardware failure, accidental deletion, or a ransomware attack. Ensure backups are also protected (e.g., encrypted).

Utilize Secure Email Gateways

Secure email gateways (SEGs) act as a checkpoint for incoming and outgoing email, providing advanced threat detection, spam filtering, data loss prevention (DLP), and encryption enforcement, strengthening overall email security posture.

Maintain Compliance

Ensure email practices and security measures comply with relevant industry regulations (e.g., GDPR, HIPAA, PCI DSS). This may involve specific archiving, encryption, or data handling requirements.

What are the examples of email security?

Here are some examples of email security measures and technologies in practice:

• A company uses a secure email program (like Gmail or Microsoft 365) and requires users to enter a strong password and use two-factor authentication before accessing their email.
• The company uses encryption software or protocols like TLS for transit encryption and S/MIME for end-to-end encryption of emails containing sensitive data sent over the internet.
• The company configures email authentication standards like DMARC (at enforcement p=reject or p=quarantine), SPF, and DKIM to prevent email spoofing and ensure unauthorized emails are rejected or flagged as spam.
• Deploying antivirus and anti-malware solutions that scan all incoming email attachments and links.
• Using an email sandbox to safely analyze suspicious attachments before they reach the user’s inbox.
• Implementing spam filters to block unsolicited and potentially malicious emails.
• Utilizing Microsoft 365 Advanced Threat Protection (ATP) or similar services for enhanced protection against phishing, malware, and other advanced threats.
• The company defends against phishing and business email compromise attacks by also integrating cloud email security solutions or secure email gateways.
• Conducting regular security awareness training for employees to recognize threats like phishing, spear phishing, whaling, and BEC attempts.
• Implementing BIMI to display verified logos alongside authenticated emails, enhancing recipient trust.

Enhancing Email Security with DMARC, SPF & DKIM

Even if you know what email security is and how important it is for your business, you may still fall short of providing optimum protection against domain impersonation and spoofing without robust authentication. That’s when DMARC, a widely adopted email authentication, policy, and reporting protocol, becomes essential. It is an advanced security mechanism designed specifically to protect businesses against email spoofing and phishing by building upon SPF and DKIM. If you want to secure your email communications against fraudulent use of your domain, DMARC is the most efficient standard for this purpose. 

By implementing DMARC with an enforcement policy (reject or quarantine), you instruct receiving email servers on how to handle emails claiming to be from your domain that fail SPF or DKIM authentication checks, ensuring that illegitimate emails are less likely to reach the recipient’s inbox.

DMARC utilizes two foundational technologies, SPF and DKIM, leveraging their verification results to make policy decisions.

SPF identifies authorized sending servers by checking the IP address of the sending server against a published list in the domain’s DNS records.

DKIM creates a digital signature within the email header, linked to the domain. This signature is verified by the receiving server using a public key published in the sender’s DNS, confirming the message hasn’t been altered and the domain owner authorized the sending. DMARC adds an alignment check, ensuring the domain used in these checks matches the visible “From” address domain.

How Does DMARC Level Up Email Security?

DMARC significantly enhances email security because it provides a mechanism for domain owners to control how unauthenticated emails using their domain are handled and provides valuable feedback through reports.

The result is that DMARC provides a solid foundation for managing email authentication, preventing unauthorized use of your domain, and protecting your brand reputation, while also giving you visibility into your email ecosystem.

Here is how DMARC spruces up email security:

1. DMARC focuses on authenticating the sender’s domain based on SPF and DKIM results and alignment, specifically targeting domain spoofing used in phishing and BEC attacks. It allows domain owners to explicitly state a policy (none, quarantine, reject) for emails failing these checks.
2. It provides reporting capabilities (aggregate and forensic reports) that give domain owners insight into which emails are passing or failing authentication checks, helping identify legitimate sending sources and potential abuse of their domain.
3. It uses established DNS mechanisms for policy publication and relies on widespread adoption by receiving mail servers, making it a scalable solution.
4. By enforcing authentication, DMARC helps protect recipients from fraudulent emails impersonating trusted brands, thereby reducing the success rate of phishing and spoofing attacks.
5. DMARC works with all types of email providers and can be implemented for both small businesses and large enterprises. Its policies (p=none, p=quarantine, p=reject) allow for a gradual rollout, starting with monitoring (p=none) and progressing to enforcement.

Benefits of using Email Security Services

Implementing robust email security, often through specialized services or platforms, offers significant benefits beyond just DMARC. Comprehensive email security services typically provide layered protection, including advanced threat detection, anti-spam and anti-malware filtering, data loss prevention, encryption, archiving, and expert support for configuring protocols like DMARC, SPF, and DKIM correctly.

These services help organizations stay ahead of evolving threats, ensure compliance, reduce the burden on internal IT teams, and provide centralized management and reporting. Utilizing such services enhances overall security posture, protects brand reputation, improves email deliverability for legitimate messages, and reduces the risk of costly breaches and attacks.

The DMARC protocol itself, as a core component of modern email security, requires sending domains to publish policies via DNS. Receiving servers check incoming emails against these policies using SPF and DKIM results. If authentication fails and the DMARC policy dictates enforcement, the message may be quarantined or rejected, preventing potential harm to the recipient and protecting the sender’s domain reputation.

Email Security with PowerDMARC

No matter how much you train your employees to use email securely, the complexity of modern threats means security breaches can still occur. Implementing and managing email security protocols like DMARC, SPF, DKIM, and BIMI correctly can be challenging. If your company suffers a breach or struggles with email deliverability due to authentication issues, it can be hard to know where to start.

Therefore, you should consider using PowerDMARC’s comprehensive email authentication platform and DMARC managed services. Our team of experts specializes in email security and authentication, helping organizations protect against phishing, spoofing, BEC, and other email-based attacks.

• Using our platform, including the DMARC analyzer, you gain visibility into your email ecosystem and can easily configure and manage DMARC, SPF, DKIM, BIMI, and MTA-STS records to achieve enforcement and protect your domain.
• This helps keep your brand reputation secure from hackers who would try to impersonate your domain by sending out malicious emails.
• Proper authentication improves email deliverability and protects your customers, partners, and employees from scams sent in your name.

With DMARC and other authentication protocols configured properly through a platform like PowerDMARC, many email security problems related to domain impersonation can be mitigated, allowing you to focus on building better relationships with customers, assured that your email communications are more secure and trustworthy. Sign-up for free today!

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Ahona Rudra

Domain & Email Security Expert at PowerDMARC

Ahona is the Marketing Manager at PowerDMARC, with 5+ years of experience in writing about cybersecurity topics, specializing in domain and email security. Ahona holds a post-graduation degree in Journalism and Communications, solidifying her career in the security sector since 2019.

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